Journey with Confidence RV GPS App RV Trip Planner RV LIFE Campground Reviews RV Maintenance Take a Speed Test Free 7 Day Trial ×
 


Reply
 
Thread Tools Search this Thread Display Modes
 
Old 08-13-2021, 12:30 PM   #1
Rivet Master
 
2019 30' Classic
Belen , New Mexico
Join Date: Apr 2011
Posts: 637
Measuring Weight Distribution on Hitch

So, this summer, I figured out that I was running WAY to much WD for my truck and was causing damage to my 2019 Classic. (Thank you Vinnie for that information.)

When I bought my hitch, I bought the 1400# bars. On the ProPride jacks, I was running about 9" on the jacks. After speaking with Vinnie, I backed them down to about 7" for the trip home. Knowing that I'm not moving anywhere near 1400#, I'd like to get smaller bars for a more compliant connection, but not sure where to go.

My current setup also includes auto leveling airlift bags which does away with the need to level the trailer with the hitch (which would move way to much weight).

The truck is a 2006 Dodge Ram 2500 Quad Cab so a heavy duty truck.

Here are three weigh tickets. the last two are from today. the first is no WD applied and the second is about 6" of jack. How much weight am I moving? I want to say 380lb based on the rear axle.

the first ticket is just the truck but is about 200lbs heavier than I was running today. (2nd person in cab and ladder in back).

By the way, there was no porpoising of the truck at highway speeds even without WD applied.

ProPride has 600# and 1000# bars in stock, but not the 800# that I thought I wanted. I'm wondering if I can get by with the 600# bars.
Attached Thumbnails
Click image for larger version

Name:	Screen Shot 2021-08-13 at 12.28.56 PM.png
Views:	33
Size:	43.6 KB
ID:	401768  
Attached Images
  
Ephraim is offline   Reply With Quote
Old 08-13-2021, 12:44 PM   #2
"Cloudsplitter"

 
2003 25' Classic
Houstatlantavegas , Malebolgia
Join Date: Jun 2007
Posts: 20,000
Images: 1
Welcome Aboard...👍

You are only moving 300lb is there a reason for that?
I replace all but 100 back to the steering axle.
1200lb TW, scale

860lb receiver wt with WD set
560 to the FA
160 to the AS
720 moved
I use 1000lb bars on a Hensley Arrow.

Bob
🇺🇸
Attached Thumbnails
Click image for larger version

Name:	45111EBE-A943-48BD-AC2C-B2A10D817BEB_1_201_a.jpeg
Views:	35
Size:	586.7 KB
ID:	401769   Click image for larger version

Name:	88E7A667-6EB2-4C9B-884B-E6E04A5C5C85_1_201_a.jpeg
Views:	43
Size:	559.7 KB
ID:	401770  

Click image for larger version

Name:	029A1F8D-DC6F-4FF4-8C5B-8A48D27CA5A7_1_201_a.jpeg
Views:	38
Size:	569.4 KB
ID:	401771   Click image for larger version

Name:	CC40C8DA-C328-4DC1-9F66-6C5093B5D87B_1_201_a.jpeg
Views:	39
Size:	561.4 KB
ID:	401772  

__________________
I’m done with ‘adulting’…Let’s go find Bigfoot.
ROBERT CROSS is offline   Reply With Quote
Old 08-13-2021, 01:08 PM   #3
Rivet Master
 
2019 30' Classic
Belen , New Mexico
Join Date: Apr 2011
Posts: 637
Quote:
Originally Posted by ROBERT CROSS View Post
You are only moving 300lb is there a reason for that?
I replace all but 100 back to the steering axle.
1200lb TW, scale

860lb receiver wt with WD set
560 to the FA
160 to the AS
720 moved
I use 1000lb bars on a Hensley Arrow.

Bob
🇺🇸
The 6" was just to put some WD so I could get some weight measurements. I've yet to figure out how much I need or want. I had been adjusting to get rid of the porpoising I was experiencing, but then I replaced the shocks and that went away completely. I'm not even sure I need any now, but I definitely don't want to give up the ProPride. Coming home from California this summer with 7" on the jacks gave a pretty good ride, but that was before I replaced the shocks.

I've learned so much since I started this and now I feel I'm back to square one on figuring out what I need. So much of what I thought I learned was wrong on weight distribution. Ugh.

The squat is taken care of by the air bags and I'm struggling to figure out how much I really need. It seems only about 640# between the front wheel weights when completely unloaded and hitched but no WD. I can't really feel any difference in handling when steering (other than just what the towing does)
Ephraim is offline   Reply With Quote
Old 08-13-2021, 02:57 PM   #4
"Cloudsplitter"

 
2003 25' Classic
Houstatlantavegas , Malebolgia
Join Date: Jun 2007
Posts: 20,000
Images: 1
Quote:
Originally Posted by Ephraim View Post
The squat is taken care of by the air bags and I'm struggling to figure out how much I really need.
That may be the main concern.
The 'squat' should be taken care of with the weight distribution, NOT the air suspension.👍

Bob
🇺🇸
__________________
I’m done with ‘adulting’…Let’s go find Bigfoot.
ROBERT CROSS is offline   Reply With Quote
Old 08-13-2021, 03:05 PM   #5
Rivet Master
 
2019 30' Classic
Belen , New Mexico
Join Date: Apr 2011
Posts: 637
Quote:
Originally Posted by ROBERT CROSS View Post
That may be the main concern.
The 'squat' should be taken care of with the weight distribution, NOT the air suspension.👍

Bob
🇺🇸
While that may work on a 1/2 ton truck, it doesn't really work on a 3/4+ truck. It is virtually impossible to restore all the weight back to the front on this ram. I was running 9+ inches and was wrecking my Airstream. I was on the verge of front end separation when Vinnie caught it and showed it to me. That was with the 1400# bars. It made for a very stiff connection between the truck and trailer. Softening that connection up with less WD puts much less torque on the Airstream frame. You can visually see it as you apply or remove tension.

At this point, I'm firmly convinced that the "restore weight" argument on a 3/4+ ton truck is not valid and will eventually wreck your Airstream. Each truck may be different. I know that the Dodge Ram series in 2006 had one of the stiffest, least forgiving frames and suspensions of all the major truck companies. That may be the difference, but the fact remains, I can't restore that weight without destroying the Airstream and indeed, I'm not even sure I need to. I wouldn't give up the 3P sway elimination for anything, I'm just not sure what to do with the WD right now. 300-400lbs seems trivial.
Ephraim is offline   Reply With Quote
Old 08-13-2021, 03:49 PM   #6
"Cloudsplitter"

 
2003 25' Classic
Houstatlantavegas , Malebolgia
Join Date: Jun 2007
Posts: 20,000
Images: 1
Quote:
Originally Posted by Ephraim View Post
While that may work on a 1/2 ton truck, it doesn't really work on a 3/4+ truck. It is virtually impossible to restore all the weight back to the front on this ram. I was running 9+ inches and was wrecking my Airstream. I was on the verge of front end separation when Vinnie caught it and showed it to me. That was with the 1400# bars. It made for a very stiff connection between the truck and trailer. Softening that connection up with less WD puts much less torque on the Airstream frame. You can visually see it as you apply or remove tension.

At this point, I'm firmly convinced that the "restore weight" argument on a 3/4+ ton truck is not valid and will eventually wreck your Airstream. Each truck may be different. I know that the Dodge Ram series in 2006 had one of the stiffest, least forgiving frames and suspensions of all the major truck companies. That may be the difference, but the fact remains, I can't restore that weight without destroying the Airstream and indeed, I'm not even sure I need to. I wouldn't give up the 3P sway elimination for anything, I'm just not sure what to do with the WD right now. 300-400lbs seems trivial.
Werks on my 2500 Burb.
3/4 has little to do with it, if the TV is too stiff it's time for a new TV.
If you've got squat it can't be that stiff.

If 300 is all you want to move and you're doing with air suspension active, get the lightest bars, WD should be set without air assist.

Bob
🇺🇸
Attached Thumbnails
Click image for larger version

Name:	0A86007B-49D6-442D-94C4-AECCABC1C604_1_201_a.jpg
Views:	38
Size:	363.9 KB
ID:	401790  
__________________
I’m done with ‘adulting’…Let’s go find Bigfoot.
ROBERT CROSS is offline   Reply With Quote
Old 08-13-2021, 05:12 PM   #7
Rivet Master
 
dznf0g's Avatar
 
2007 30' Classic
Oswego , Illinois
Join Date: Jul 2010
Posts: 13,657
Images: 5
OK, so I'll Give this a stab, as I just installed my new Propride 1000 with V2 jacks...replacing my Hensley, also with 1000# bars. I have spent several days at the scales and updating the data on my spreadsheet. My first glance at your comments leaves me with...don't go below 1k bars. (I also have a 30 Classic, albeit much older than yours.

I have a Silverado double cab 1500 Maxtow with 143.5" wheelbase and 47.24" overhang between Rear axle center and receiver opening. The AS is 223.37" from ball to center between the axles. Your numbers will most assuredly be different, but this will give you an idea of the weight shifts with 1k bars.

So here are some numbers:

4" showing on the jacks = 240# removed from the RA; 160# returned to FA; 80# to TA. This with 704# of bar end force (352# per bar)

3" showing on the jacks = 360# removed from RA; 240# returned to FA; 120# to TA. This with 1075# of bar end force (537.5# per bar)

2" showing on the jacks = 480# removed from RA; 320# returned to FA; 160# to TA. This with 1410# of bar end force (705# per bar)

Remember that the bar rating is PER BAR, not for the pair.

This is the range that I will be running in and the range I used with my HAHA, although there are subtle differences in the bars and dimensions. 2" and 4" are outliers. I will be running 2.5" to 3.5", depending how the truck and trailer are loaded for a particular trip.

Most folks are over hitched, IMHO, after severely crunching a lot of numbers.
__________________
-Rich-

"If the women don't find you handsome, they should at least find you handy." - Red Green
dznf0g is online now   Reply With Quote
Old 08-13-2021, 05:13 PM   #8
Rivet Master
 
dznf0g's Avatar
 
2007 30' Classic
Oswego , Illinois
Join Date: Jul 2010
Posts: 13,657
Images: 5
Stay tuned, hit submit by mistake, more to come. (post 7 fixed now)
__________________
-Rich-

"If the women don't find you handsome, they should at least find you handy." - Red Green
dznf0g is online now   Reply With Quote
Old 08-13-2021, 05:28 PM   #9
Rivet Master
 
dznf0g's Avatar
 
2007 30' Classic
Oswego , Illinois
Join Date: Jul 2010
Posts: 13,657
Images: 5
I should also mention, the above numbers are with 4 washers of head tilt.
__________________
-Rich-

"If the women don't find you handsome, they should at least find you handy." - Red Green
dznf0g is online now   Reply With Quote
Old 08-13-2021, 05:48 PM   #10
Rivet Master
 
dznf0g's Avatar
 
2007 30' Classic
Oswego , Illinois
Join Date: Jul 2010
Posts: 13,657
Images: 5
Also, Just to alleviate certain confusion....V1 jacks (which I assume OP has, from his 1st post) count the inches exactly opposite of V2 jacks. They both have 10" of available travel but pull opposite housings (V1 pulls with the upper (outer housing) and V2 pulls with the lower (inner housing). So (although not precisely) 10" on V1 = 0" on V2. 0" on V1 = 10" on V2.

So when OP says he ran 7", that roughly corresponds with 3" on my V2 explanation above.....but he has 1400" bars.....much stiffer and much more bar end force per inch of travel on the jacks.
__________________
-Rich-

"If the women don't find you handsome, they should at least find you handy." - Red Green
dznf0g is online now   Reply With Quote
Old 08-13-2021, 05:51 PM   #11
jcl
Rivet Master
 
Currently Looking...
Vancouver , British Columbia
Join Date: Oct 2012
Posts: 4,579
Quote:
Originally Posted by Ephraim View Post
So, this summer, I figured out that I was running WAY to much WD for my truck and was causing damage to my 2019 Classic. (Thank you Vinnie for that information.)

When I bought my hitch, I bought the 1400# bars….
There are two different concepts here, the amount of WD and the bar stiffness,

The amount of WD usually refers to how much front axle load restoration, or weight shift. It is a result of the bar stiffness and the bar tension. I don’t think you have too much WD.

The bar rating refers to the stiffness, or compliance, in the setup, not the amount of WD. You had stiff bars. You should go softer.

Agree with posters above. You were only moving 300 lbs. you could move more. But with more compliant bars, that wouldn’t subject the trailer to the same shock loading. Doesn’t RAM call for 50% FALR on the 2500?

Your old shocks were weak or ineffective. Your airbags are likely confusing the issue. They are not an asset. Listen to Bob.
jcl is offline   Reply With Quote
Old 08-13-2021, 06:50 PM   #12
"Cloudsplitter"

 
2003 25' Classic
Houstatlantavegas , Malebolgia
Join Date: Jun 2007
Posts: 20,000
Images: 1
^
X2

It goes all the way back to Inland Andy, he always preached....you want the most compliant lash-up with the lowest rated tapered bars that will move the necessary weight.

Bob
🇺🇸
__________________
I’m done with ‘adulting’…Let’s go find Bigfoot.
ROBERT CROSS is offline   Reply With Quote
Old 08-13-2021, 07:03 PM   #13
Rivet Master
 
dznf0g's Avatar
 
2007 30' Classic
Oswego , Illinois
Join Date: Jul 2010
Posts: 13,657
Images: 5
Quote:
Originally Posted by ROBERT CROSS View Post
^

X2



It goes all the way back to Inland Andy, he always preached....you want the most compliant lash-up with the lowest rated tapered bars that will move the necessary weight.



Bob

[emoji631]
Funny you should mention that. I was just looking at the chart from his shop bar end force vs. deflection chart yesterday. He started me down a math path that still continues today. That was 2011 or 12 that we all discussed that. I wonder how to search for that thread.
__________________
-Rich-

"If the women don't find you handsome, they should at least find you handy." - Red Green
dznf0g is online now   Reply With Quote
Old 08-13-2021, 08:33 PM   #14
"Cloudsplitter"

 
2003 25' Classic
Houstatlantavegas , Malebolgia
Join Date: Jun 2007
Posts: 20,000
Images: 1
Quote:
Originally Posted by dznf0g View Post
Funny you should mention that. I was just looking at the chart from his shop bar end force vs. deflection chart yesterday. He started me down a math path that still continues today. That was 2011 or 12 that we all discussed that. I wonder how to search for that thread.

Like THIS?...enjoy.

Bob
🇺🇸
__________________
I’m done with ‘adulting’…Let’s go find Bigfoot.
ROBERT CROSS is offline   Reply With Quote
Old 08-13-2021, 08:47 PM   #15
Rivet Master
 
dznf0g's Avatar
 
2007 30' Classic
Oswego , Illinois
Join Date: Jul 2010
Posts: 13,657
Images: 5
Quote:
Originally Posted by ROBERT CROSS View Post
Like THIS?...enjoy.

Bob
🇺🇸
That's not the one. I'm talking about the one where Inland Andy posted the results of his bar end force vs, deflection tests for a number of hitch manufacturers and ratings.

This was the graph he sent me, but there was a lot of good conversation surrounding his efforts

Hitch data base.xlsx
__________________
-Rich-

"If the women don't find you handsome, they should at least find you handy." - Red Green
dznf0g is online now   Reply With Quote
Old 08-13-2021, 09:23 PM   #16
Rivet Master
 
2019 30' Classic
Belen , New Mexico
Join Date: Apr 2011
Posts: 637
Quote:
Originally Posted by jcl View Post
There are two different concepts here, the amount of WD and the bar stiffness,

The amount of WD usually refers to how much front axle load restoration, or weight shift. It is a result of the bar stiffness and the bar tension. I don’t think you have too much WD.

The bar rating refers to the stiffness, or compliance, in the setup, not the amount of WD. You had stiff bars. You should go softer.

Agree with posters above. You were only moving 300 lbs. you could move more. But with more compliant bars, that wouldn’t subject the trailer to the same shock loading. Doesn’t RAM call for 50% FALR on the 2500?

Your old shocks were weak or ineffective. Your airbags are likely confusing the issue. They are not an asset. Listen to Bob.
the difference in FAL between unhitched and hitched (no WD) is only 640#. If I'm moving 50% like the dodge manual says, the the 300+ # that I moved with 6" (V1 jacks) would satisfy that. Perhaps that is why it felt good while driving today.

BTW, is that 50% of loaded or unloaded config? Meaning do I measure that as 50% using the lower unhitched FAL or the higher fully loaded unhitched FAL?

In may, I have weigh tickets where the truck alone (fully loaded, unhitched was 3540 FAL, 4140 RAL) and the hitched weight w/WD was (3360 FAL, 5200 RAL, 8680 TAL) but that was with 9-9.5" on the V1 jacks. don't know what the no WD weights were.

the heaviest I've been was last fall where we basically took it all on a month long vacation.

Loaded unhitched: 3600 FAL, 4280 RAL
Loaded hitched: 3540 FAL, 5220 RAL, 8940 TAL.

This is the trip where the damage to the trailer showed up. Vinnie said too much WD on too stiff a connection.
Ephraim is offline   Reply With Quote
Old 08-13-2021, 09:30 PM   #17
Rivet Master
 
2019 30' Classic
Belen , New Mexico
Join Date: Apr 2011
Posts: 637
Quote:
Originally Posted by dznf0g View Post
4" showing on the jacks = 240# removed from the RA; 160# returned to FA; 80# to TA. This with 704# of bar end force (352# per bar)

3" showing on the jacks = 360# removed from RA; 240# returned to FA; 120# to TA. This with 1075# of bar end force (537.5# per bar)

2" showing on the jacks = 480# removed from RA; 320# returned to FA; 160# to TA. This with 1410# of bar end force (705# per bar)

Remember that the bar rating is PER BAR, not for the pair.

This is the range that I will be running in and the range I used with my HAHA, although there are subtle differences in the bars and dimensions. 2" and 4" are outliers. I will be running 2.5" to 3.5", depending how the truck and trailer are loaded for a particular trip.

Most folks are over hitched, IMHO, after severely crunching a lot of numbers.
How are you finding the bar end force values?
Ephraim is offline   Reply With Quote
Old 08-14-2021, 06:46 AM   #18
Rivet Master
 
dznf0g's Avatar
 
2007 30' Classic
Oswego , Illinois
Join Date: Jul 2010
Posts: 13,657
Images: 5
"the difference in FAL between unhitched and hitched (no WD) is only 640#. If I'm moving 50% like the dodge manual says, the the 300+ # that I moved with 6" (V1 jacks) would satisfy that. Perhaps that is why it felt good while driving today."

Yes, based upon the limited info I read, that is correct. For my 1500, an 80% return is more appropriate.

"BTW, is that 50% of loaded or unloaded config? Meaning do I measure that as 50% using the lower unhitched FAL or the higher fully loaded unhitched FAL?"

The amount of WD to return the proper percentage is fluid. The jack setting would be different with a light load, empty, or a heavy load. In a nutshell, it is achieved ready to go camping.

"In may, I have weigh tickets where the truck alone (fully loaded, unhitched was 3540 FAL, 4140 RAL) and the hitched weight w/WD was (3360 FAL, 5200 RAL, 8680 TAL) but that was with 9-9.5" on the V1 jacks. don't know what the no WD weights were."

Loaded with no WD is a critical number to determine how much WD is needed for a particular load.
__________________
-Rich-

"If the women don't find you handsome, they should at least find you handy." - Red Green
dznf0g is online now   Reply With Quote
Old 08-14-2021, 07:38 AM   #19
Rivet Master
 
dznf0g's Avatar
 
2007 30' Classic
Oswego , Illinois
Join Date: Jul 2010
Posts: 13,657
Images: 5
Quote:
Originally Posted by Ephraim View Post
How are you finding the bar end force values?
It is a complicated series of math equations, based upon a total of 5 passes over the scales. These are used as a baseline whereby, as I load (weighed items in the truck or trailer, by location) I can determine needed changes to jack position.

The five passes are: truck alone, truck and trailer w/no WD, truck and trailer with 5" jack showing, truck and trailer with 4" showing, and truck and trailer with 3" showing.

Since spring rates (for a single stage spring) are theoretically linear, the data in between and surrounding these jack settings can be mathematically determined.

Once one has all the weights and measurements one can determine the input force needed to achieve weight movement through a series of lever principle calculations. Bar end force determination is only really useful in determining the correct spring bar weight rating and isn't necessarily needed for daily determination of WD jack position selection.

This brings up an important point. Many folks, including some dealer/merchant professionals have the definition of bar rating all wrong, IMO.

Some believe the rating should be matched to the actual TW of the trailer...."1000# TW, so the minimum you should get is 1200 or 1400". THIS IS WRONG.

Others believe the spring bar rating is tied to the amount of weight one is trying to move off the rear axle. THIS IS WRONG.

Springs are rated to their individual ability to function with a given input force (bar end force for WD springs). This is pretty straight forward with an automotive spring.....the suspension of a direct vertical load. With a WD spring, through a series of "levered" beam points, you have a relatively huge input force, resulting in relatively small numerical results. (The forces actually are equal, but that's another story).

So, in my case, I have 1000# bars X 2 = 2000# of WD spring capability. If I were to load my rig to where 2" of jack was showing (bar end force of 1410#) I am well within the spring capability.

But wait, you say,...800# bars would have 1600# of capability, so why not go down. The above example shows STATIC input forces. When you in a dynamic situation....severe dips, bridge approaches at speed, etc. the input forces to the bar end can, and do rise dramatically.

So why not get 1400# bars and forget it (like the bigger is better crowd espouses). Well.......I just point to the front end separation issue as one of the reasons, but what do I know?
__________________
-Rich-

"If the women don't find you handsome, they should at least find you handy." - Red Green
dznf0g is online now   Reply With Quote
Old 08-14-2021, 11:02 AM   #20
Rivet Master
 
2019 30' Classic
Belen , New Mexico
Join Date: Apr 2011
Posts: 637
Quote:
Originally Posted by dznf0g View Post
It is a complicated series of math equations, based upon a total of 5 passes over the scales. These are used as a baseline whereby, as I load (weighed items in the truck or trailer, by location) I can determine needed changes to jack position.
I would love to see these equations. Being somewhat of a nerd, my curiosity is peaked.

I think I'm beginning to get a handle on things now. Next time I load up, I need to allot some scale time to make multiple passes over the scale so I can develop a chart of forces. The hope is that in the future, I can make a double pass over the scales. On the way to the storage lot, I'll measure the loaded, unhitched truck and then after hitching up, make a reweigh of the hitched noWD truck/Airstream. then using the chart, know exactly how to set the jacks for that trip.
Ephraim is offline   Reply With Quote
Reply


Currently Active Users Viewing This Thread: 1 (0 members and 1 guests)
 
Thread Tools Search this Thread
Search this Thread:

Advanced Search
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off


Similar Threads
Thread Thread Starter Forum Replies Last Post
MEASURING Tongue Weight CanoeU70 Towing, Tow Vehicles & Hitches 14 12-15-2018 09:28 AM
Measuring forces at the hitch boondockdad Hitches, Couplers & Balls 55 05-08-2015 11:33 AM


Featured Campgrounds

Reviews provided by

Disclaimer:

This website is not affiliated with or endorsed by the Airstream, Inc. or any of its affiliates. Airstream is a registered trademark of Airstream Inc. All rights reserved. Airstream trademark used under license to Social Knowledge LLC.



All times are GMT -6. The time now is 06:21 PM.


Powered by vBulletin® Version 3.8.8 Beta 1
Copyright ©2000 - 2024, Jelsoft Enterprises Ltd.